Rolled metal foil treatment



Dec. 4, 1962 Filed Nov. 19,

w. J. NEUHAUSER ET A]. 3,067,073

ROLLED METAL FOIL TREATMENT 1959 2 Sheets-Sheet l WILL/AM JOHN NEUHAUSER ROLAND M4LENT/NE l/lLL/ERS fiu w T L INV EN TORS.

Dec. 4, 1962 w. J. NEUHAUSER ET AL 3,067,073

ROLLED METAL FOIL TREATMENT 2 Sheets-Sheet 2 Filed Nov. 19, 1959 IIIPIJVIflIIIIIIIIIII INVENTORS.

W/LL/AM JOHN NEUHAUSER ROLAND VALENTINE V/LL/ERS United States haircut N [EQQ 3,057,073

Patented Dec. 4, 19%2 3,067,073 ROLLED METAL FOIL TREATMENT William John Neuhauser and Roland Valentine Vilhers,

Louisville, Ky., assi nors to Reynolds Metals Company, Richmond, Va, a corporation of Delaware Filed Nov. 119, 1959, Ser. No. 854,061 3 Claims. (Cl. 148-43) This invention relates to the production of metal foil. More particularly, this invention relates to the treatment of rolled aluminum foil by annealing so as to improve the flexibility of the foil and remove rolling oil from the foil to improve the surface characteristics thereof as regards subsequent adhesion thereto of printing ink and labels. The annealing of the roll of aluminum foil is carried out preparatory to subsequent operations such as slitting, laminating to paper stock, printing, et cetera.

In the production of aluminum foil, aluminum billets are rolled down to foil stock by passing the metal a number of times through hot rolling mills and then finally through one or more cold mills until a thickness of 0.5- 0.7 millimeter is reached. This foil stock, as it is called, is usually annealed before cold rolling further to foil gauges. In the cold rolling the metal is reduced to about half thickness with each pass through the cold mills. The final aluminum foil produced by the cold rolling is a thin sheet below about 0.15 millimeter in thickness.

A great deal of heat is generated during both the hot and cold rolling, and has to be taken away evenly so that hot spots do not develop to cause roll distortion and bellies in the foil.

To remove this heat, oil is sprayed on the rolls, not only cooling them but also lubricating the metal. The metal coming from the rolling mill is oily with the lubricant, and because of the work which is being done on it, is hard and springy. A limited quantity of foil is used in this hard condition because the hard toll is less liable to distortion and damage than is annealed foil.

The oil on the hard foil makes good adhesion of paper to foil difiicult, and the foil is generally too springy and relatively brittle. It is usual therefore, to anneal aluminum foil to give it relatively dead folding characteristics. Annealing consists of heating the foil in spool or roll form for a number of hours at temperatures not far short of dull red heat, namely about 650 degrees Fahrenheit to about 800 degrees Fahrenheit. The annealing process reduces brittleness and removes a major portion of the lubricating oil by vaporization. Also, the annealing process gives a completely sterile surface to the aluminum foil.

Heretofore, in annealing a cylindrical roll of aluminum foil wound on a core or stem, it has been found that during annealing, the amount of heat entering the ends of the roll of aluminum foil is approximately three times the amount of heat entering the roll through the curved cylindrical surface thereof. This non-uniform flow of heat produces undesirable effects in the foil. It has also been found that, after annealing according to prior procedures, the end surface areas of the rolled foil have residual oil stain therein which makes the foil unacceptable for many uses. The oil stain on the edges of the foil makes the foil unsightly. Further, the oil stain i11- terferes with proper printing of the foil.

In accordance with the present invention, these difliculties are overcome by wrapping the roll of aluminum foil in a package which provides for substantially uniform heat flow through the roll and eliminates the oil stain on the edge surfaces of the foil.

For a better understanding of the invention and its other objects, advantages and details, reference is now made to the present preferred embodiment of the inven- 2. tion which is shown, for purposes of illustration only, in the accompanying drawings.

In the drawings:

FIG. 1 is a vertical section illustrating the initial step in forming a package according to the invention wherein end sheets of aluminum foil are placed adjacent each end of a roll of metal foil wound upon a core;

FIG. 2 is a vertical section illustrating a subsequent step in forming a package according to the invention wherein asbestos discs are placed at each end of the roll adjacent the end sheets of aluminum foil;

FIG. 3 is an end elevation of the combination of elements illustrated in FIG. 2;

FIG. 4 is a vertical section illustrating a subsequent step in forming a package according to the invention wherein the edge portions of the aluminum foil end sheets are folded over the edges of the asbestos discs;

FIG. 5 is an end elevation of the combination of elements illustrated in FIG. 4;

FIG. 6 is an end elevation illustrating a subsequent step in forming a package according to the invention wherein four wrapping sheets of aluminum foil are placed adjacent the cylindrical periphery of the roll;

FIG. 7 is a vertical section illustrating a subsequent step in forming a package according to the invention wherein the four cover sheets of aluminum foil have been wrapped around the cylindrical periphery of the roll;

FIG. 8 is a vertical section illustrating the complete package wherein the ends of the four wrapping sheets have been tucked in to engage the core and the package has been suspended in an annealing furnace; and,

FIG. 9 is a fragmentary vertical elevation of one end of the package illustrated in FIG. 8, shown on an enlarged scale, with the elements exploded, wherein the arrows indicate the paths of flow of the residual rolling oil vapors during annealing.

Referring to the drawings, the formation of a package of a roll of aluminum foil suitable for annealing is illustrated in FIGS. 1 to 8. In FIG. 1, a roll 20 of metal foil, such as aluminum foil, is illustrated wound upon a core having ends 22 and 24 projecting from opposite ends of roll 20. The foil of roll 20 is springy and relatively brittle and is coated with oil applied during the previous rolling. A square end sheet of aluminum foil 26 is placed adjacent one end of roll 29 with the core end 22 extending through a central aperture in the end sheet 26. Similarly, a square end sheet of aluminum foil 28 is placed adjacent the other end of the roll 26 with the core end 24 extending through a central aperture in the sheet 26. The end sheets 26 and 28 have a thickness of about 0.0007 inch. Among the other thicknesses which can be employed are from about 0.00025 inch to about 0.0025 inch.

Next, referring to FIG. 2, a porous, heat-insulating, circular, asbestos disc 30 is placed adjacent the end foil sheet 26 with the core end 22 extending through a central aperture in the disc 30. Similarly, a. porous, heatinsulating, circular, asbestos disc 32 is placed adjacent the end foil sheet 28 with the core end. 24 extending through a central aperture in asbestos disc 32. As seen in FIG. 3, the square end sheets 26 and 28 have greater widths than the diameter of roll 20 and discs 30 and 32 so that the edge portions of the end sheets 26 and 28 extend outwardly beyond the discs. The discs 30 and 32 are formed of 32-pound asbestos.

Referring to FIGS. 4 and 5, the corners 34 of the foil end sheet 26 are folded over the disc 30 and pressed against the outer surface of disc 30. In like manner, the corners 36 of foil end sheet 28 are folded over the disc 3-2. and pressed against the outer surface of disc 32.

Thereafter, two superposed cover or wrapping sheets and 42 are placed over the cylindrical periphery of I} roll 2b with their ends extending for a substantial distance beyond one end of roll 28. Another pair of superposed cover or wrapping sheets 44 and 46 are placed over the periphery of roll 2% with their inner ends overlapping the sheets 4% and 42 and their outer ends extendingfor a substantial distance beyond the other end of roll 20. The wrapping sheets 44 d2, 44 and 46 are formed of aluminum foil of (H3012 inch thickness. It will be seen in FIG. 7 that in the center or" roll 2%, the wrapping is four sheets thick.

The extending ends of the wrapping sheets are then folded and tucked inwardly toward the core ends 22 and 24. Referring to FIG. 8, a tucked sealing rib 50 is formed by packing the ends of wrapping sheets 43 and 42 around the core end 22. Similarly, a tucked sealing rib 52 is formed by packing the ends of Wrapping sheets 44 and &6 around the core end 24. Thus, the aluminum foil package 66 is formed as shown in FIG. 8 and suspended in a dry annealing furnace 62.

For clarity of illustration, the scale of elements shown in the drawing is distorted. Some of the elements are shown to an enlarged scale of thickness.

The aluminum foil package 64 is dry annealed in furnace 62 at temperatures from about 650 degrees Fahrenheit to about 800 degrees Fahrenheit. The annealing reduces the brittleness of the foil in roll 28. Further, the annealing gives it dead folding characteristics, that is, reduces the springiness of the foil. The annealing also vaporizes the rolling oil from the roll Ztl and produces foil free of end roll stain.

Each element of the package plays a part in achieving these advantageous results. Referring to FIG. 9, the arrows indicate the probable paths of flow of the oil vapors as they leave the roll 21?. The asbestos discs 39 and 32 equalize the heat flow through the roll 28 during the annealing cycle. It has been determined experimentally that during annealing the amount of heat entering the ends of a roll of aluminum foil is approximately three times the amount of heat entering the roll through its cylindrical peripheral area. The insulating value of the asbestos discs 3d and 32 effectively reduces this 3 to 1 heat flow ratio to a point where substantially uniform heat flow through the roll is obtained which is extremely desirable in aluminum foil dry annealing.

Further, the asbestos discs 3% and 32 absorb some of the residual rolling oil which has been driven from the roll 20 during the annealing cycle.

The end sheets 26 and 28 prevent staining of the ends of roll Ztl by the residual rolling oil that is driven from the foil roll 2%) during the annealing cycle. While the invention is not to be limited by theoretical explanations of its operation, the following are possible modes in which the end sheets 26 and 28 prevent end roll stain: 1) The major portion of rolling oil vapor is absorbed by the asbestos discs but a certain amount remains unabsorbed. This unabsorbed vapor condenses on the end sheets 26 .and 28 instead of on the ends of roll 20. (2)

4 The residual rolling oil absorbed by the asbestos discs is prevented from migrating to the ends of roll 20 by the end sheets 26 and 28 acting as barriers between the asbestos discs and the roll 23.

The wrapping sheets 49, 42, 44, and 469 secure the asbestos discs 38 and 32 and the end foil sheets 26 and 2% in position adjacent the ends of foil roll 29.

Thus it will be seen that the invention provides a metal foil roll packaged for uniform heating in an annealing furnace wherein the package elements produce substantially comp ete removal of residual rolling oil from the foil roll and also provide for uniform heating of the roll during annealing.

While a present preferred embodiment of the invention has been illustrated and described, it will be recognized that the invention can be otherwise variously embodied and practiced Within the scope of the following claims.

We claim:

1. The process of preparing a roll of metal foil for annealing, comprising placing an end sheet of gas-impermeable material adjacent each end of said metal foil roll; placing a plate of heat-insulating porous material adjacent each said end sheet on the side of said end sheet remote from said roll; and wrapping the foregoing assembly with at least one sheet of gas-impermeable metal foil.

2. A process for treating aluminum foil comprising the steps; placing an end sheet of aluminum foil adjacent each end of a cylindrical, spirally-Wound roll of aluminum foil; placing an asbestos disc adjacent each said end sheet of aluminum foil on the side of said end sheet of aluminum foil remote from said roll; wrapping an overlapping plurality of sheets of aluminum foil around said roll with ends of said sheets extending beyond the ends of said roll; tucking the ends of said' sheets inwardly to encase the discs of aluminum foiland asbestos within the wrap ping sheets; and annealing the packaged foil.

3. A process for the treatment of rolled metal foil which comprises placing an end sheet of gas-impermeable material adjacent each end of a roll of metal foil; placing a plate of heat-insulating porous material adjacent each of said end sheet on the side thereof remote from said roll; wrapping said roll with at least one sheet of gasimpermeable metal foil and encasing the end sheets and porous material; and heating the packaged material at temperatures between about 650 F. and 800 F. for a period of time sufiicient to anneal said roll of metal foil.

References Cited in the file of this patent UNITED STATES PATENTS 1,652,371 Miller Dec. 13, 1927 2,109,204 Wilson Feb. 22, 1938 2,595,375 Weirich May 6, 1952 2,607,476 Rockefeller Aug. 19, 1952 2,646,877 Scholl July 28, 1953 2,797,177 Keller June 25, 1957 2,843,514 Kunz July 15, 1958 1 na wwa 

1. THE PROCESS OF PREPARING A ROLL OF METAL FOIL FOR ANNEALING, COMPRISING PLACING AN END SHEET OF GAS-IMPERMEABLE MATERIAL ADJACENT EACH END OF SAID METAL FOIL ROLL; PLACING A PLATE OF HEAT-INSULATING POROUS MATERIAL ADJACENT EACH SAID END SHEET ON THE SIDE OF SAID END SHEET REMOTE FROM SAID ROLL; AND WRAPPING THE FOREGOING ASSEMBLY WITH AT LEAST ONE SHEET OF GAS-IMPERMEABLE METAL FOIL. 